U.S. patent number 5,310,354 [Application Number 08/028,772] was granted by the patent office on 1994-05-10 for integral ground terminal and tail shield.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Joseph A. Oswald, Jr..
United States Patent |
5,310,354 |
Oswald, Jr. |
May 10, 1994 |
Integral ground terminal and tail shield
Abstract
The present invention relates to integral ground terminals and
tail shields for cross talk control between signal carrying
conductors in connectors and, in particular, where the connector is
a right angle receptacle or a right angle header.
Inventors: |
Oswald, Jr.; Joseph A.
(Mechanicsburg, PA) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
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Family
ID: |
25317894 |
Appl.
No.: |
08/028,772 |
Filed: |
February 17, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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854159 |
Mar 19, 1992 |
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Current U.S.
Class: |
439/108;
439/607.05 |
Current CPC
Class: |
H01R
13/6585 (20130101); H01R 24/50 (20130101); H01R
2103/00 (20130101); H01R 12/724 (20130101) |
Current International
Class: |
H01R
12/16 (20060101); H01R 12/00 (20060101); H01R
13/00 (20060101); H01R 13/646 (20060101); H01R
013/658 () |
Field of
Search: |
;439/101,108,607,608 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Paumen; Gary F.
Attorney, Agent or Firm: Woodcock Washburn Kurtz Mackiewicz
& Norris
Parent Case Text
This is a continuation-in-part of application Ser. No. 07/854,159
filed Mar. 20, 1992, now abandoned.
Claims
What is claimed is:
1. A connector for interconnecting a mating connector and a circuit
assembly, comprising:
an insulative housing;
a plurality of terminals arranged in rows and columns in the
housing;
at least one integral ground terminal and tail shield in one of the
columns and comprising:
a first contact end portion for contacting a mating terminal
contact portion in the mating connector;
a first, substantially flat, longitudinal, tail portion connected
to the first contact end portion;
a second, substantially flat, longitudinal, tail portion connected
to the first tail portion at a bend;
a second contact end portion terminating the second tail portion,
the second contact end portion for being connected to the circuit
assembly;
a first, substantially flat, shield member integrally connected to
one of the first tail portion and the second tail portion, the
first shield member non-integrally electrically contacting the
other one of the first tail portion and the second tail portion,
the first shield member being substantially perpendicular to the
first tail portion and the second tail portion; and
a second, substantially flat, shield member integrally connected to
one of the first tail portion and the second tail portion, the
second shield member non-integrally electrically contacting the
other one of the first tail portion and the second tail portion,
the second shield member being substantially perpendicular to the
first tail portion and the second tail portion; and
the first and second shield members and the first and second tail
portions of the integral ground terminal and tail shield defining a
pocket for enclosing tails of a plurality of the terminals in the
same column as the integral ground terminal and tail shield.
2. The connector of claim 1, wherein:
the first tail portion has a first flange and a second flange, the
flanges extending from distal sides of the first tail portion;
the first shield member non-integrally contacting the first flange;
and
the second shield member non-integrally contacting the second
flange.
3. The connector of claim 1, wherein:
the first shield member being integrally connected to the first
tail portion and non-integrally connected to the second tail
portion.
4. The connector of claim 1, wherein:
the first shield member being non-integrally connected to the first
tail portion and integrally connected to the second tail
portion.
5. The connector of claim 1, further comprising:
a first displacement contact having a slot receiving the second
tail portion, the first displacement contact connected to the first
shield member at a bend; and
a second displacement contact having a slot receiving the second
tail portion, the second displacement contact connected to the
second shield member at a bend.
6. The connector of claim 1, wherein:
the first contact end portion being a socket or pin shaped.
7. An integral ground terminal and tail shield, comprising:
a first contact end portion for contacting a mating terminal
contact portion;
a first, substantially flat, longitudinal, tail portion connected
to the first contact end portion;
a second, substantially flat, longitudinal, tail portion connected
to the first tail portion at a bend;
a second contact end portion terminating the second tail portion,
the second contact end portion for being connected to a circuit
assembly;
a first, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the first shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
first shield member being substantially perpendicular to the first
tail portion and the second tail portion;
a second, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the second shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
second shield member being substantially perpendicular to the first
tail portion and the second tail portion;
the second tail portion has a first flange and a second flange, the
flanges extending from distal sides of the second tail portion;
the first shield member non-integrally contacting the first flange;
and
the second shield member non-integrally contacting the second
flange.
8. An integral ground terminal and tail shield for use in a
connector having a plurality of terminals arranged in rows and
columns, comprising:
a first contact end portion for contacting a mating terminal
contact portion;
a first, substantially flat, longitudinal, tail portion connected
to the first contact end portion;
a second, substantially flat, longitudinal, tail portion connected
to the first tail portion at a bend;
a second contact end portion terminating the second tail portion,
the second contact end portion for being connected to a circuit
assembly;
a first, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the first shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
first shield member being substantially perpendicular to the first
tail portion and the second tail portion; and
a second, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the second shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
second shield member being substantially perpendicular to the first
tail portion and the second tail portion,
such that when the integral ground terminal and tail shield is used
as one of the terminals in one of the columns of the connector
having the plurality of terminals arranged in rows and columns, the
first and second shield members and the first and second tail
portions define a pocket for enclosing tails of a plurality of the
terminals in the same column as the integral ground terminal and
tail shield; wherein:
the second tail portion has a first flange and a second flange, the
flanges extending from distal sides of the second tail portion;
the first shield member non-integrally contacting the first flange;
and
the second shield member non-integrally contacting the second
flange.
9. A connector for interconnecting a mating connector and a circuit
assembly, comprising:
an insulative housing;
a plurality of terminals arranged in rows and columns in the
housing;
at least one integral ground terminal and tail shield in one of the
columns and comprising:
a first contact end portion for contacting a mating terminal
contact portion in the mating connector;
a first, substantially flat, longitudinal, tail portion connected
to the first contact end portion;
a second, substantially flat, longitudinal, tail portion connected
to the first tail portion at a bend;
a second contact end portion terminating the second tail portion,
the second contact end portion for being connected to the circuit
assembly;
a first, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the first shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
first shield member being substantially perpendicular to the first
tail portion and the second tail portion;
a second, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the second shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
second shield member being substantially perpendicular to the first
tail portion and the second tail portion;
the first and second shield members and the first and second tail
portions of the integral ground terminal and tail shield defining a
pocket for enclosing tails of a plurality of the terminals in the
same column as the integral ground terminal and tail shield;
the second tail portion has a first flange and a second flange, the
flanges extending from distal sides of the second tail portion;
the first shield member non-integrally contacting the first flange;
and
the second shield member non-integrally contacting the second
flange.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to integral ground terminals and tail
shields for cross talk control between signal carrying conductors
in connectors and, in particular, where the connector is a right
angle receptacle or a right angle header.
2. Description of Related Art
With the advance of technology, a high density of electronic
circuits and components can be located on a printed wiring board or
printed circuit board (PCB). Along with this miniaturization of
electronic circuits and components, electrical connectors are
needed to electrically and mechanically interconnect one PCB, such
as a back panel or mother board, to one or more other PCBs, such as
daughter boards. Further, it is typically desirable for such
connectors to have a high signal density capacity. That is, the
connectors should permit a high number of signals to pass through
the connector per unit volume of the connector. However, electrical
signals carried on a conductor can interfere with a signal carried
on an adjacent conductor.
This interfering electrical effect that an electrical signal
carried on a given conductor exerts on a signal carried on an
adjacent conductor is referred to as "cross talk." Controlling this
cross talk is especially important in high density connectors. Such
control can be implemented in a variety of ways.
One method of controlling cross talk is to connect certain
terminals in a high density connector to conductive areas of a
printed circuit board that are in turn grounded or connected to a
predetermined ground potential. This solution is external to the
connector.
U.S. Pat. No. 4,655,518 (to Lennart B. Johnson et al.), U.S. Pat.
No. 4,686,607 (to Lennart B. Johnson) and U.S. Pat. No. 4,869,677
(to Lennart B. Johnson et al.) disclose a daughter board/backplane
assembly with contact elements dedicated for grounding purposes.
Header contact elements have contacts that can be connected to
ground or a predetermined potential on a backplane. The header
contact elements have other spring contacts carried by an inside
header wall for touching contacts carried by a right angle
receptacle outer wall. Other contacts are integral with and
perpendicular to the contacts carried by the right angle receptacle
outer wall for connection to the daughter board.
U.S. Pat. No. 4,601,527 issued to Timothy A. Lemke discloses an
internal shielding structure for connectors, specifically in
vertical and right angle headers. The shielding structure includes
a ground strip affixed to a mating surface of a header housing. The
shielding structure further includes an elongated conductive spring
contact with contact beams that extend in holes of side walls of
the housing, lock tabs that connect to the ground strip and ground
bars for connection to a grounded chassis.
U.S. Pat. No. 4,824,383 issued to Timothy A. Lemke discloses a
shielding structure in connectors or plug-type terminators for
either a multiple conductor cable or a multiple tracing substrate
that electrically isolates individual or groups of contact elements
in the terminator to prevent or minimize cross talk between
adjacent conductors and to prevent or minimize degradation of
signal transmission. The terminator includes a ground structure
with generally U-shaped channels. Contact elements extend into the
channels. The ground structure is connected to a predetermined
potential, rather than dedicating some of the contact elements for
this purpose.
U.S. Pat. No. 4,898,546 issued to Richard A. Elco et al. discloses
a ground shield device for right angle connectors. A different one
of the shield devices straddles alternate columns of contact
elements in the connector. Each shield device clips to a tail of
one of the contact elements straddled by the shield device. The
shield devices are connected to ground or a predetermined
potential.
It is an object of this invention to provide an integral ground
terminal and tail shield for use in a high density electrical
connector for electrically and mechanically interconnecting
electronic circuits and/or components controlling cross talk within
the connector.
Furthermore, it is an object of this invention to provide an
integral ground terminal and tail shield for use in a high density
angled or right angle electrical receptacle or header for
electrically and mechanically interconnecting a circuit assembly
and a plurality of terminals arranged in rows and columns in a
mating connector to control cross talk thereby to reduce or
minimize degradation of signal transmission within the receptacle
or header.
These and other objects are satisfied in the subject invention
which will be clear from the following description.
SUMMARY OF THE INVENTION
The invention relates to an integral ground terminal and tail
shield, comprising:
a first contact end portion for contacting a mating terminal
contact portion;
a first, substantially flat, longitudinal, tail portion connected
to the first contact end portion;
a second, substantially flat, longitudinal, tail portion connected
to the first tail portion at a bend;
a second contact end portion terminating the second tail portion,
the second contact end portion for being connected to a circuit
assembly;
a first, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the first shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
first shield member being substantially perpendicular to the first
tail portion and the second tail portion; and
a second, substantially flat, shield member integrally connected to
at least one of the first tail portion and the second tail portion,
the second shield member at least electrically contacting the other
one of the first tail portion and the second tail portion, the
second shield member being substantially perpendicular to the first
tail portion and the second tail portion.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be more fully understood from the following
detailed description thereof in connection with accompanying
drawings described as follows.
FIG. 1 is a perspective view of a header, a receptacle and a pair
of circuit assemblies exploded from one another, the header and
receptacle having integral ground terminals and tail shields in
accordance with the present invention.
FIG. 2 is an enlarged perspective view of a first embodiment of an
integral ground terminal and tail shield for use in a receptacle in
accordance with the present invention.
FIG. 3 is a perspective view of a second embodiment of the integral
ground terminal and tail shield for use in a receptacle in
accordance with the present invention which is similar to the first
embodiment of FIG. 2 with displacement contacts.
FIG. 4 is a perspective view of a third embodiment of an integral
ground terminal and tail shield for use in a receptacle in
accordance with the present invention.
FIG. 5 is a perspective view of a fourth embodiment of an integral
ground terminal and tail shield for use in a receptacle in
accordance with the present invention.
FIG. 6 is a perspective view of a fifth embodiment of an integral
ground terminal and tail shield for use in a header in accordance
with the present invention.
FIG. 7 is a perspective view of a sixth embodiment of an integral
ground terminal and tail shield for use in a header in accordance
with the present invention.
FIG. 8 is a perspective view of a seventh embodiment of an integral
ground terminal and tail shield for use in a header in accordance
with the present invention.
FIG. 9 illustrates a method of manufacturing the integral ground
terminal and tail shield of the present invention in a flat strip
of metal.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
Throughout the following detailed description, similar reference
characters refer to similar elements in all figures of the
drawings.
Referring to FIG. 1, there is illustrated a connector assembly
comprising a first circuit assembly 10, a first connector 12 for
connecting to the first circuit assembly 10, a second connector 14
for connecting to the first connector 12, and a second circuit
assembly 16 for connecting to the second connector 14. The first
connector 12 is depicted as a receptacle having an insulative
housing 18 and a plurality of terminals 20 arranged in rows and
columns in the housing. The second connector 14 is depicted as a
header having an insulative housing 22 and a plurality of terminals
24 arranged in rows and columns in the housing. Both the receptacle
12 and the header 14 are depicted as angled or right angled
connectors such that their terminals 20,22 have bends or bent
portions 26. In accordance with the present invention, both the
receptacle 12 and the header 14 includes at least one integral
ground terminal and tail shield 100 in at least one of the columns
of the terminals 20,22. Any number of columns of the terminals 20
or 24 can be positioned between adjacent ones of the integral
ground terminals and tail shields 100. The receptacle 12 or the
header 14 can have any number of the integral ground terminals and
tail shields 100 including only one. Preferably and as depicted in
FIG. 1, there is one of the integral ground terminals and tail
shields 100 in every other column of the terminals 20,22.
Preferably and as depicted in FIG. 1, the integral ground terminals
and tail shields 100 are in the place of the longest terminal 20,22
in the respective column of terminals 20,22 and shield the tails of
all other terminals in the respective column. However, the integral
ground terminals and tail shields 100 can be in the place of any of
the terminals 20,22 in a column of terminals 20,22. Further, the
integral ground terminals and tail shields 100 can shield the tails
of a plurality, but less than all, of the terminals in the same
column. The connector assembly may also include spacers 28 for
maintaining the spacing between the terminals 20,22 of the
connectors 12,14 before the terminals 20,22 are inserted in and
soldered to plated-through holes 30 in the circuit assemblies
10,16.
FIG. 2 is an enlarged perspective view of a first embodiment 200 of
the integral ground terminal and tail shield 100 for use in the
receptacle 12 in accordance with the present invention. Referring
to FIG. 2, the integral ground terminal and tail shield 200
comprises a first contact end portion 202, a first tail portion
204, a second tail portion 206, a second contact end portion 208, a
first shield member 210, and a second shield member 212. The first
contact end portion 202 is for contacting a mating terminal contact
portion, such as, a first end portion of one of the terminals 24 of
the header 14 illustrated in FIG. 1. The first contact end portion
202 can mate with a mating contact end portion. However, the first
contact end portion 202 is illustrated in FIG. 2 as a socket that
can be manufactured from a flat sheet of metal. The first tail
portion 204 is a substantially flat, longitudinal, tail portion 204
integrally connected to the first contact end portion 202. The
second tail portion 206 is a substantially flat, longitudinal, tail
portion 206 integrally connected to the first tail portion 204 at a
bend or bent portion 214. The bend 214 can be any angle, such as 45
degrees or 90 degrees. The second contact end portion 208
integrally terminates the second tail portion 206. The second
contact end portion 208 can have any shape as long as it is adapted
to be connected to the circuit assembly 10, such as, by soldering
to plated-through holes 30 in the circuit assembly 10. FIG. 2
illustrates the second end portion 208 as a flat solder tail end
portion with inclined lead-in edges to facilitate insertion into
the plated-through holes 30.
The first tail portion 204 and the second tail portion 206 can have
other bends or bent portions in them. Preferably, the first tail
portion 204 and the second tail portion 206 are in the shape of a
flat strip having substantially parallel sides or edges.
The first shield member 210 is integrally connected to at least one
of the first tail portion 204 and the second tail portion 206. In
the first embodiment illustrated in FIG. 2, the first shield member
210 is integrally connected to the first tail portion 204. Further,
the first shield member 210 is at least electrically contacting the
other one of the first tail portion 204 and the second tail portion
206. In the first embodiment illustrated in FIG. 2, the first
shield member 210 is electrically and non-integrally contacting the
second tail portion 206. As used herein, the term "integral" means
formed as a unit with another part. This can be accomplished if
both parts are made from the same part and never divided into two
distinct parts. Alternatively, two parts that are originally two
distinct parts become integral when they are connected together in
any permanent fashion, such as by soldering or welding. As used
herein, the term "non-integral" means two parts are in contact with
or connected to each other such that the two parts can be separated
without significant effort or destruction of the parts.
Similarly, the second shield member 212 is integrally connected to
at least one of the first tail portion 204 and the second tail
portion 206. In the first embodiment illustrated in FIG. 2, the
second shield member 212 is integrally connected to the first tail
portion 204. Further, the second shield member 212 is at least
electrically contacting the other one of the first tail portion 204
and the second tail portion 206. In the first embodiment
illustrated in FIG. 2, the second shield member 212 is electrically
and non-integrally contacting the second tail portion 206.
In the first embodiment, the first tail portion 204 has a first
flange 216 and a second flange 218. The flanges 216,218 extend from
the distal sides or edges of the first tail portion 204. The first
shield member 210 integrally and electrically connects to the first
flange 216. The second shield member 212 integrally and
electrically connects to the second flange 218. The second tail
portion 206 has a first flange 220 and a second flange 222. The
flanges 220,222 extend from the distal sides or edges of the second
tail portion 206. The first shield member 210 non-integrally and
electrically contacts the first flange 220. The second shield
member 212 non-integrally and electrically contacts the second
flange 222.
The first shield member 210 is substantially perpendicular to the
first tail portion 204 and the second tail portion 206. The second
shield member 212 is substantially perpendicular to the first tail
portion 204 and the second tail portion 206. The second shield
member 212 is spaced from and substantially parallel to the first
shield member 210. The first shield member 210, the second shield
member 212, the first tail portion 204 and the second tail portion
206 define a pocket 224 for enclosing tails of the terminals 20 in
the same column as the integral ground terminal and tail shield
200.
FIG. 3 illustrates a second embodiment 300 of the integral ground
terminal and tail shield 100 of the present invention. The second
embodiment 300 is the same as the first embodiment 200, except the
second embodiment 300 includes a first displacement contact 326 and
a second displacement contact 328. The first displacement contact
326 has a slot for receiving in an interference fashion and, thus,
electrically contacting the second tail portion 306. The first
displacement contact 326 is integrally connected to the first
shield member 310 at a bend. The second displacement contact 328
has a slot for receiving in an interference fashion and, thus,
electrically contacting the second tail portion 306. The second
displacement contact 328 is integrally connected to the second
shield member 312 at a bend. Displacement contacts, like
displacement contacts 326,328, can be on any of the embodiments
disclosed herein. Displacement contacts, like displacement contacts
326,328, can even be used to connect the shield members to the
first tail portion, such as, in the embodiment illustrated in FIG.
4.
Referring to FIG. 4, there is illustrated a third embodiment 400 of
the integral ground terminal and tail shield 100 of the present
invention. The third embodiment 400 can be the same as the first
embodiment 200, except in the third embodiment 400 the first shield
member 410 non-integrally and electrically contacts the first
flange 416. The second shield member 412 non-integrally and
electrically contacts the second flange 418. The first shield
member 410 integrally and electrically connects to the first flange
420. The second shield member 412 integrally and electrically
connects to the second flange 422.
FIG. 5 illustrates a fourth embodiment 500 of the integral ground
terminal and tail shield 100 of the present invention. The fourth
embodiment 500 can be the same as the first embodiment 200, except
the first and second shield members 510,512 have first shield
members or sections 530 and second shield members or sections 532.
The first sections 530 are integrally connected to the first and
second flanges 516,518 of the first tail portion 504. The second
sections 532 are integrally connected to the first and second
flanges 520,522 of the second tail portion 506. The first and
second sections 530,532 of each shield member 510,512 are
non-integrally and electrically contacting each other. Since the
first members or sections 530 are non-integrally and electrically
contacting the second members or sections 532 and since the second
members or sections 532 are integrally a part of the second tail
portion 506 through its flanges 520,522, then it follows that the
first members or sections 530 are non-integrally and electrically
contacting the second tail portion 506 (through the second members
or sections 532). Similarly, since the second members or sections
532 are non-integrally and electrically contacting the first
members or sections 530 and since the first members or sections 530
are integrally a part of the first tail portion 504 through its
flanges 516,518, then it follows that the second members or
sections 532 are non-integrally and electrically contacting the
first tail portion 504 (through the first members or sections
530).
FIGS. 6-8 illustrate a fifth, a sixth and a seventh embodiment 600,
700 and 800, respectively, of the integral ground terminal and tail
shield 100 of the present invention. The fifth, sixth and seventh
embodiments 600, 700 and 800, respectively, illustrate three
alternative designs for the first contact end portion designated by
numbers 602, 702 and 802, respectively. Any one of these first
contact end portions 602, 702 and 802 can be on any of the
embodiments disclosed in this specification. The fifth and sixth
embodiments 600 and 700, respectively, are the same as the the
first embodiment 200, except their first contact end portions
202,602,702 are different. The seventh embodiment 800 is the same
as second embodiment 300, except their first contact end portions
302,702 are different.
The first contact end portion 602 of the fifth embodiment 600 is
rolled from flat stock of sheet metal forming a cylindrical body
634 with a longitudinal slit 636. The first contact end portion 602
has either a claim shell tip or a tapered tip 638 to facilitate
insertion of the first contact end portion 602 into a mating
connector.
The first tail portion 702 of the sixth embodiment 700 is formed
from flat stock of sheet metal having a first thickness which is
the desired thickness of the first tail portion 702. The sheet
metal is milled to remove a layer of the metal off the sheet to
form the lower surface of the first contact end portion 704 and the
rest of the integral ground terminal and tail shield 700. Then the
integral ground terminal and tail shield 700 is cut or trimmed from
the milled sheet. The first contact end portion 702 is preferably
cut to have a substantially square cross section, perpendicular to
its longitudinal axis. The first contact end portion 702 also has a
tapered tip 738 to facilitate insertion of the first contact end
portion 702 into a mating connector.
The first contact end portion 802 of the seventh embodiment 800 is
a cylindrical pin which is welded or soldered to the first tail
portion 804. The first contact end portion also has a conical tip
838 to facilitate insertion of the first contact end portion 802
into a mating connector.
Each of the embodiments of the integral ground terminal and tail
shield 100 disclosed herein can be made from flat stock of a
suitable metal. To illustrate, FIG. 9 is a plan view of flat stock
which has been initially trimmed to a shape from which the integral
ground terminal and tail shield 200 can be formed through one or a
series of subsequent trimming steps and bending or folding steps.
In one of the subsequent trimming steps, the remainder of the first
contact end portion 202 is cut on dashed lines 940 from a first or
front carrying strip 942. The second contact end portion 208 is cut
from a strip connected to a second or rear carrying strip 944.
Dashed lines 946 indicate regions where the flat metal is folded to
form the shape of the integral ground terminal and tail shield 200
illustrated in FIG. 2.
Those skilled in the art, having the benefit of the teachings of
the present invention as hereinabove set forth, can effect numerous
modifications thereto. These modifications are to be construed as
being encompassed within the scope of the present invention as set
forth in the appended claims.
* * * * *